1968 merc 20 hp

Looking for some advice here. The issue is fuel. The motor runs out of fuel. I have been up and down the fuel tank, fuel lines, carb, replaced the fuel pump diaphram, primer bulb and hose.
filters are clean. I have put alot of time and effort into finding the source of this problem. At the very least, I am fed up! But, being stubborn I'm determined to fix it. I have come to the conclusion that the issue lies somewhere in the fuel pump system. I checked for vac leaks and check for any plugged openings and replaced the hoses. Found nothing. Whats my next step? I am thinking I may have to check the reed valves. That should be an adventure. Dont really want to go there, but i will. So if you can think of anything please let me know. thanks, JBK

Re: 1968 merc 20 hp

Unless you're getting blow-back out of the carb, the reeds are likely fine.

Does the motor keep running if you pump the primer bulb? How long does it run until it runs out?

Re: 1968 merc 20 hp

Fuel tank vent clear and working? Primer bulb installed with the arrow pointing toward the motor?

Re: 1968 merc 20 hp

Did you look at the check valves in the fuel pump? I once had one that was stuck open and it would not pump fuel.

Re: 1968 merc 20 hp

I have noticed quite a bit of fuel blow back out of the carb as well as out between where the Intake bolts on to the motor. dang this doesnt sound good. I have the arrow pointing the right way on primer bulb and check valves are good
As for the tank, its a metal tank that vents through the cap. all clear there. Thanks, keep it coming please

Re: 1968 merc 20 hp

another note. it only does this after it stalls out

Re: 1968 merc 20 hp

There should be no fuel coming around the intake (carb mount) bolts. Check for air leaks... Should be a gasket between the carb flange and the crankcase.

Re: 1968 merc 20 hp

I may have misspoken. Looks like the fuel is running down from somewhere higher. Looks like source is barried beneath flywheel and all that. All bolts tight.

Re: 1968 merc 20 hp

may be the reeds after all? fuel spilling out of the carb and coming from somewhere else (source barried)

Re: 1968 merc 20 hp

Fuel/oil coming from up top would indicate the top seal is shot or blown out. You'll have to pop the flywheel to check it out.